The International Security Assistance Force(ISAF) says a key leader of the Haqqani militant group has been arrested in Afghanistan ' s mountainous eastern province of Khost."An Afghan and coalition security force arrested a Haqqani (network) leader during an operation in Musa Khel district, Khost province, today," ISAF said in a statement issued on Saturday. "The leader is accused of having operational control over multiple extremist cells and has personally led fighters in attacks against Afghan and coalition forces," it added. The Pakistan-based Haqqani network has conducted many attacks on US-led forces in eastern Afghanistan and the capital Kabul. Washington has often pressed Pakistan to take on the Haqqani network, the Afghan group fighting Western occupation forces in Afghanistan. Pakistan says its forces are too stretched battling its own militants and cannot chase members of the Haqqani network in the semi-autonomous North Waziristan region, bordering Afghanistan. On Friday, Afghan security officials said they had defused a massive truck bomb in Kabul, the biggest of its kind discovered in the war-torn country. The National Directorate of Security (NDS) said it found nearly eight tons of explosives, wired and ready for detonation, hidden in cement bags in a truck, a trademark method of the Haqqani network. "This truck bomb could have destroyed an area around 1.5 km (in radius). Now can you imagine that what kind of catastrophe this would be?" NDS spokesman Shafiqullah Tahiri told a news conference. Five suspected bombers were killed and two others arrested during a pre-dawn raid by security forces on Wednesday. The US-led war in Afghanistan began in 2001. The offensive removed the Taliban from power, but insecurity continues to rise across Afghanistan, despite the presence of about 100,000 US-led troops.